1. Field of the Invention
The present invention relates to a medical elongate member, a method of manufacturing the same, and an apparatus for manufacturing the same.
2. Description of the Related Art
A variety of medical elongate members such as guide wires and catheters are employed for various uses such as examinations of living bodies, treatments, etc.
Catheters are used in treatment of portions at which open surgeries are difficult or which require minimal invasiveness to the body, for example, PTCA (Percutaneous Trasluminal Coronary Angioplasty), or in examination such as cardioangiography. Guide wires are used to guide a catheter to the objective cite in the living body.
A guide wire used in PTCA is inserted, with its distal end protruding from the distal end of a balloon catheter, into the vicinity of the target stenosis portion together of its coronary with the balloon catheter. The thinner guide wire is first passed through the stenosis part, so as to guide the balloon catheter while widening the stenosis portion. In the case of PTA (Percutaneous Treansluminal Angioplasty), also, the guide wire is used to guide the balloon catheter to a stenosis portion, like in PTCA, in order to achieve recanalization of a stenosis/occulusion portion of a femoral, iliac, renal, shunt or other peripheral blood vessel.
A guide wire is inserted into the lumen of a catheter or the inner cavity of an endoscope and is moved in its longitudinal direction or rotated in use. In this case, a lower sliding resistance (lower frictional resistance) is preferred for attaining enhanced steerability of the guide wire.
From this point of view, there has been proposed a guide wire in which a fluororesin coating layer containing a particulate material added thereto is formed on the surface of a metallic wire (See FIGS. 1 and 2 of US patent Publication No. 2006-0073264 A1). According to the guide wire, a plurality of projections are formed in the surface of the fluororesin coating layer due to the presence of the particulate material. Therefore, the area of contact of the guide wire with the inner surface of the catheter is reduced, whereby the frictional resistance is lowered.
In the guide wire described in U.S. patent Publication No. 2006-0073264 A1, however, it happens the distribution of the particulate material in the surface of the fluororesin coating layer is not uniform. Therefore, the frictional resistance of the guide wire may vary locally or may vary from product to product. This makes difficult the operation (steering) of the guide wire, which relies on subtle sensation.
In addition to the above, there has also been proposed a guide wire in which a plurality of metallic wires are bundled and twisted and a fluororesin coating layer is formed on the surface of the twisted bundle so as to reduce the area of contact with the inner surface of a catheter (See FIG. 2 of patent No. U.S. Pat. No. 6,251,085 B1).
In the guide wire described in patent No. U.S. Pat. No. 6,251,085 B1, however, not the fluororesin coating layer on the surface but the metallic wires themselves fundamental to the guide wire are worked. Consequently, the guide wire obtained shows a weakened durability.